Wrong unit in ResourceUsage.maxRSS

[XeroAlpha]

What does this PR do?

ResourceUsage.maxRSS is reported in kilobytes. See libuv api documentation.

• Documentation or TypeScript types (it's okay to leave the rest blank in this case)
• Code changes

[robobun]

Thanks for the report. This was accurate when it was opened: Subprocess.resourceUsage().maxRSS returned the raw ru_maxrss value, which is kilobytes on Linux (and PeakWorkingSetSize / 1024 on Windows) but bytes on macOS, so on Linux the documented unit was wrong.

It was fixed on the implementation side instead. Since #36087, src/spawn_sys/spawn_process.rs normalizes the value to bytes on every platform: ru_maxrss is multiplied by 1024 on non-Apple targets, and the Windows path stores PeakWorkingSetSize without dividing it. A quick check with a current build: for the same child process, process.resourceUsage().maxRSS inside the child reports 26964 (kilobytes, as in Node) and the parent's proc.resourceUsage().maxRSS reports 27611136, exactly 1024 times that. test/harness.ts also asserts the bytes unit now.

So the current docs (docs/runtime/child-process.mdx, which replaced docs/api/spawn.md in #24201) and the ResourceUsage.maxRSS JSDoc in packages/bun-types/bun.d.ts are correct as written, and changing them to kilobytes would now be wrong. Closing this one.